Semiconductor device

ABSTRACT

In order to suppress defective lead forming and defective mounting, a semiconductor device includes a sealing body which has a square planar shape, a semiconductor chip which lies within the sealing body, and a plurality of leads which are electrically connected with electrodes of the semiconductor chip, which extend inside and outside the sealing body and which are arrayed along latera of the sealing body, wherein an outer lead portion of each of the leads is such that a root part which protrudes out of the sealing body is formed at a lead width being equal to or greater than a lead thickness, and that a mounting part which joins to the root part through an intermediate part is formed at a lead width being less than the lead thickness.

FIELD OF THE INVENTION

The present invention relates to a semiconductor device, and moreparticularly to techniques which are effective when applied to asemiconductor device having a plurality of leads that extend inside andoutside a sealing body.

BACKGROUND OF THE INVENTION

A semiconductor device of QFP (Quad Flat Package) type, for example, hasbeen known as one of semiconductor devices well suited for increasingthe number of pins. In general, the semiconductor device of the QFP typeis manufactured by an assembling process employing a lead frame.Concretely, it is manufactured in such a way that a semiconductor chipis mounted through an adhesive on the chip mounting surface of a die pad(also termed a “tab”) which is supported on the frame member of the leadframe through supporting leads, that electrodes (also termed “bondingpads”) formed on the circuit forming surface of the semiconductor chipand the inner lead portions (also termed the “inner leads”) of leads(leads for connections) supported by the frame member of the lead frameare thereafter electrically connected by pieces of conductive wire, thatthe semiconductor chip, the die pad, the supporting leads, the innerlead portions of the connection leads, and the wire pieces arethereafter encapsulated with a sealing body which is made of aninsulating resin, that tie bars (also termed “dam bars”) which tie theadjacent ones of the connection leads are thereafter cut away, that theouter lead portions (also termed the “outer leads”) of the connectionleads are thereafter subjected to a plating treatment, that the outerlead portions of the connection leads are thereafter cut away from theframe member of the lead frame, that the outer lead portions of theconnection leads are thereafter shaped into a gull-wing shape which isone of flat packaging (surface-mounted) lead shapes, and that thesupporting leads are thereafter cut away from the frame member of thelead frame.

Each of the outer lead portions of the connection leads molded into thegull-wing shape is constructed having a root part which protrudes out ofthe sealing body, an intermediate part which bends downwards from theroot part, and a mounting part which extends from the intermediate partin the same direction as the extending direction of the root part. Suchmounting parts are employed as terminal parts for external connectionsin the case where the semiconductor device is soldered and mounted ontoa mounting substrate.

Meanwhile, in the semiconductor device of the QFP type, the number ofpins is increasing more and more as a circuit system to be included inthe semiconductor chip becomes higher in the density of integration andlarger in the number of functions. A lead array in the outer leadportions of the connection leads is set at a narrower pitch with theincrease in the number of pins.

The narrower pitch of the outer lead portions is promoted by narrowingthe interval between the adjacent connection leads and the width of eachof the connection leads. Therefore, when the semiconductor device issoldered and mounted onto the mounting substrate, such defectivemounting is liable to occur that a solder bridge appears across themounting parts of a certain one of the outer lead portions and the outerlead portion adjoining the certain outer lead portion, to short-circuitthe corresponding adjacent leads.

Besides, when the outer lead portions are molded into the gull-wingshape, such defective lead molding is liable to occur that the outerlead portions are molded into a state where they bend in the directionof arraying the connection leads (laterally of the outer lead portions),due to their insufficient mechanical strength. The defective leadmolding forms a factor for incurring the short-circuit defect that themounting part of a certain one of the outer lead portions comes intotouch with the mounting part of the outer lead portion adjoining thecertain outer lead portion, and also a factor for incurring theappearance of the solder bridge in the mounting operation.

As a technique for solving such problems ascribable to the narrowedpitch of the outer lead portions, by way of example, one wherein thelead width of the shoulder part (root part) of the outer lead of eachconnection lead is set broader than that of the base part (mountingpart) thereof is disclosed in the official gazette of Japanese PatentLaid-open No. 350003/1994 (laid open on Dec. 22, 1994). According tothis technique, the shoulder parts of the outer leads are endowed withsufficient rigidity. Therefore, even when mechanical stresses have actedon the shoulder parts in the forming operation, the connection leads donot deform into greatly discrepant geometries, so that a conductiondefect ascribable to the touch between the connection leads adjoiningeach other, a conduction defect ascribable to the insufficient touch ofthe connection lead with an electrode, etc. can be prevented fromoccurring. Moreover, a pitch of predetermined dimension is ensured bynarrowing the lead width of the base parts of the outer leads.Therefore, in a case where a semiconductor integrated circuit device issoldered to a printed circuit board, the solder bridge due to which theadjacent connection leads are electrically connected by a solder can besimultaneously prevented from appearing.

SUMMARY OF THE INVENTION

A point to be explained below, however, is not considered in thetechnique mentioned above.

The bend of the outer lead portions in the connection lead arrayingdirection in the forming operation is governed by the lead width of theroot parts of the outer lead portions. In a case where the lead width ofthe root parts is equal to or greater than the lead thickness thereof,the mechanical strength of the root parts in the connection leadarraying direction is high, and hence, the bend of the outer leadportions in the connection lead arraying direction in the formingoperation can be suppressed to some extent. However, in a case where thelead width of the root parts is less than the lead thickness thereof,the mechanical strength of the root parts in the connection leadarraying direction is low, and hence, the bend of the outer leadportions in the connection lead arraying direction in the formingoperation becomes difficult of suppression. In other words, the leadthickness of the root parts needs to be considered in order that thedefective lead forming of the outer lead portions may be suppressed bysetting the lead width of the root parts broader than the lead width ofthe mounting parts.

An object of the present invention is to provide techniques which arecapable of suppressing the defective lead forming and defective mountingof a semiconductor device.

The above and other objects and novel features of the present inventionwill become apparent from the description of this specification whenread in conjunction with the accompanying drawings.

A typical aspect of performance of the present invention is brieflysummarized as follows:

A semiconductor device comprises a sealing body which has a squareplanar shape, a semiconductor chip which lies within said sealing body,and a plurality of leads (leads for connections) which are electricallyconnected with electrodes of said semiconductor chip, which extendinside and outside said sealing body and which are arrayed along lateraof said sealing body, wherein an outer lead portion of each of saidleads is such that a root part which protrudes out of said sealing bodyis formed at a lead width being equal to or greater than a leadthickness, and that a mounting part which joins to said root partthrough an intermediate part is formed at a lead width being less thanthe lead thickness.

According to the above expedient, the root parts of the outer leadportions are formed at the lead width equal to or greater than the leadthickness, so that the mechanical strength of the root parts in thedirection of arraying the leads becomes higher than in case of formingthe root parts of the outer lead portions at a lead width less than thelead thickness. It is therefore possible to suppress the defective leadforming that, in a lead forming operation for the outer lead portions,these outer lead portions are shaped into a state where they bend in thelead arraying direction.

Besides, the mounting parts of the outer lead portions are formed at thelead width less than the lead thickness, so that the interval betweenthe respectively adjacent leads at the mounting parts becomes broaderthan in case of forming the mounting parts of the outer lead portions ata lead width equal to or greater than the lead thickness. It istherefore possible to suppress solder bridges which appear across themounting parts of the adjacent leads in soldering and mounting thesemiconductor device onto a mounting substrate, and to suppress thedefective mounting that the adjacent leads short-circuit.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic plan view of a semiconductor device being anembodiment of the present invention in a state where the upper part of asealing body has been removed;

FIG. 2 is a schematic sectional view taken along line A—A indicated inFIG. 1;

FIG. 3 is a schematic perspective view of the essential portions of thesemiconductor device;

FIG. 4 is a schematic plan view of a lead frame which is used in anassembling process for the semiconductor device;

FIG. 5 is an enlarged schematic plan view of essential portions shown inFIG. 4;

FIG. 6 is a schematic sectional view for explaining the lead formingstep of the semiconductor device;

FIG. 7 is a schematic sectional view for explaining he lead forming stepof the semiconductor device;

FIG. 8 is a schematic perspective view of the essential portions of thesemiconductor device in a state where this semiconductor device has beenmounted on a mounting substrate; and

FIG. 9 is a schematic perspective view of the essential portions of asemiconductor device showing a modification to the embodiment of thepresent invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Now, the construction of the present invention will be described inconjunction with embodiments in which the present invention is appliedto a semiconductor device of QFP type. Incidentally, throughout thedrawings for describing the embodiments, the same symbols are assignedto parts having the same functions, which shall be omitted from repeatedexplanation.

FIG. 1 is a schematic plan view of a semiconductor device being anembodiment of the resent invention with the upper part of a sealing bodyremoved therefrom, FIG. 2 is a schematic sectional view taken along lineA—A indicated in FIG. 1, and FIG. 3 is a schematic perspective view ofthe essential portions of the semiconductor device.

As illustrated in FIGS. 1 and 2, the semiconductor device of thisembodiment is constructed having a semiconductor chip 1, a die pad 3,four supporting leads 4, a plurality of leads for connections 5, aplurality of pieces of conductive wire 9, and the sealing body 10.

The semiconductor chip 1 lies within the sealing body 10, and is mountedthrough an adhesive on the chip mounting surface of the die pad 3 in astate where the circuit forming surface 1A of the front and rearsurfaces of this semiconductor chip faces upwards. By way of example,the semiconductor chip 1 chiefly includes a semiconductor substratewhich is made of single-crystal silicon, and insulating layers andwiring layers which are formed over the semiconductor substrate. Theplanar shape of the semiconductor chip 1 is a square shape, which is aregular square in this embodiment.

A logic circuit system, for example, is constructed as a circuit systemin the semiconductor chip 1. The logic circuit system mainly includestransistor elements formed on the principal surface of the semiconductorsubstrate, and wiring lines formed in the wiring layers.

The circuit forming surface 1A of the semiconductor chip 1 is formedwith a plurality of electrodes (bonding pads) 2 along the respectivelatera of the semiconductor chip 1 at the outer periphery thereof. Theplurality of electrodes 2 are formed in the uppermost one of the wiringlayers of the semiconductor chip 1, and they are electrically connectedthrough the wiring lines to the transistor elements constituting thecircuit system, respectively. Each of the plurality of electrodes 2 isformed of, for example, an aluminum (Al) film or an aluminum alloy film.

The die pad 3 lies within the sealing body 10. The planar shape of thedie pad 3 is, for example, a square shape, and the external size thereofis somewhat larger than that of the semiconductor chip 1.

The planar shape of the sealing body 10 is a square shape, which is aregular square in this embodiment. In order to attain a lower stress,the sealing body 10 is formed of, for example, a biphenyl-basedinsulating resin which is doped with a phenolic hardener, siliconerubber, a filler, or the like. The sealing body 10 is formed by transfermolding technology which is well suited for mass production. Thetransfer molding technology is a process wherein, using a metal moldwhich includes a pot, a runner, a pouring gate and a cavity, aninsulating resin is injected under pressure from the pot into the cavitythrough the runner as well as the pouring gate, thereby to form asealing body.

The plurality of connection leads 5 extend inside and outside thesealing body 10, respectively. The individual connection leads 5 aresuch that their inner lead portions 5A lying within the sealing body 10are arrayed along the respective latera of the semiconductor chip 1 atthe outer periphery thereof, and that their outer lead portions 5B lyingoutside the sealing body 10 are arrayed along the respective latera ofthe sealing body 10 at the outer periphery thereof.

The plurality of connection leads 5 are electrically connected throughthe wire pieces 9 to the plurality of electrodes 2 formed on the circuitforming surface 1A of the semiconductor chip 1, respectively. Each ofthe wire pieces 9 has its one end side connected to the electrode 2 ofthe semiconductor chip 1, and has its other end side connected to thedistal or front end part of the inner lead portion 5A. Gold (Au) wire,for example, is employed as the wire 9. By way of example, bonding inwhich ultrasonic vibrations are used conjointly with thermocompressionis employed as a method of connecting the wire 9.

The four supporting leads 4 lie within the sealing body 10, and arearranged outside the outer periphery of the semiconductor chip 1. Eachof the four supporting leads 4 is integral with the corresponding one ofthe four corners of the die pad 3, and extends toward the correspondingone of the four corners of the sealing body 10. Each of the foursupporting leads 4 is subjected to a bending work for locating the diepad 3 at a level lower than that of the inner lead portions 5A of theconnection leads 5.

The outer lead portions 5B of the respective connection leads 5 areshaped into, for example, a gull-wing shape which is one of flatpackaging shapes. As illustrated in FIG. 3, each of the outer leadportions 5B formed into the gull-wing shape is constructed having a rootpart 5B1 which protrudes out of the sealing body 10, an intermediatepart 5B2 which bends downwards (onto the side of the rear surface of thefront and rear surfaces of the sealing body 10) from the root part 5B1,and a mounting part 5B3 which extends in the same direction as theextending direction of the root part 5B1 from the intermediate part 5B2.The mounting part 5B3 is used as a terminal for external connection inthe case where the semiconductor device is mounted onto a mountingsubstrate with a solder. Such outer lead portions 5B are arrayed at apitch of, for example, 0.4 [mm] in this embodiment.

In the outer lead portion 5B of each connection lead 5, the lead widthW1 of the root part 5B1 is broader than the lead width W3 of themounting part 5B3. Further, the lead width W1 of the root part 5B1 isset at a dimension being equal to or greater than the lead thickness Tof the connection lead 5, whereas the lead width W3 of the mounting part5B3 is set at a dimension being less than the lead thickness T. In thisembodiment, the lead width W1 of the root part 5B1 is 0.15 [mm], thelead width W3 of the mounting part 5B3 is 0.14 [mm], and the leadthickness T of the connection lead 5 is 0.15 [mm]. In this manner, theroot parts 5B1 of the outer lead portions 5B are formed at the leadwidth W1 being equal to or greater than the lead thickness T, wherebythe mechanical strength of the root parts in the connection leadarraying direction becomes higher than in case of forming the root parts5B1 of the outer lead portions 5B at a lead width less than the leadthickness T. Besides, the mounting parts 5B3 of the outer lead portions5B are formed at the lead width W3 being less than the lead thickness T,whereby the interval between the respectively adjacent connection leadsat the mounting parts 5B3 becomes broader than in case of forming themounting parts 5B3 of the outer lead portions 5B at a lead width equalto or greater than the lead thickness T.

The outer lead portion 5B of each connection lead 5 includes a tie barseparating part 5B4 which has a lead width W2 broader than the leadwidth W1 of the root part 5B1, and which is provided at the intermediatepart 5B2. In this embodiment, the entire intermediate part 5B2 exceptthe tie bar separating part 5B4 is formed at the same lead width as thatof the mounting part 5B3.

Next, the schematic construction of a lead frame which is used in anassembling process (manufacturing process) for the semiconductor devicewill be described with reference to FIGS. 4 and 5. FIG. 4 is a schematicplan view of the lead frame, while FIG. 5 is an enlarged schematic planview of essential portions shown in FIG. 4.

As illustrated in FIG. 4, the lead frame LF is constructed having a diepad 3, four supporting leads 4, a plurality of leads for connections 5,lead support portions 7 etc., within a lead arrangement region whoseperimeter is defined by a frame member 8 and which has a square shapewhen viewed in plan. The die pad 3 lies at the central part of the leadarrangement region, and is formed in a square planar shape. Each of thefour supporting leads 4 is integral with the corresponding corner of thedie pad 3 on one end side thereof, and it is integral with the leadsupporting portion 7 provided at the corresponding corner of the leadarrangement region, on the other end side thereof. The lead supportportions 7 are integral with the frame member 8. Each of the foursupporting leads 4 is subjected to a bending work for locating the diepad 3 at a level lower than that of the connection leads 5.

The plurality of connection leads 5 are divided into four lead groups,which are disposed at the respective latera of the frame member 8 so asto surround the die pad 3. The connection leads 5 of each lead group arearrayed along the corresponding latus of the frame member 8. Besides,each of the connection leads 5 of each lead group lies near the die pad3 on one end side thereof and is integral with the frame member 8 on theother end side thereof. As illustrated in FIG. 5, the connection leads 5of each lead group are constructed of a single lead member having innerlead portions (portions surrounded with a dot-and-dash line in thefigure) 5A which are to be arranged inside a sealing body, and outerlead portions 5B which are to be arranged outside the sealing body.Also, the connection leads 5 of each lead group are tied with therespectively adjacent connection leads 5 through tie bars 6 which areprovided for the purpose of preventing a resin from flowing out when thesealing body is formed. The tie bars 6 are arranged near the root partsof the outer lead portions 5B.

In the outer lead portion 5B of each connection lead 5, an inward partlying on the side of the inner lead portion 5A with respect to the tiebar 6 is formed at a lead width being equal to or greater than a leadthickness, and an outward part lying on the side of the frame member 8with respect to the tie bar 6 is formed at a lead width being less thanthe lead thickness. In the lead frame LF of this embodiment, the leadwidth of the inward part of the outer lead portion 5B is set at 0.15[mm], the lead width of the outward part of the outer lead portion 5B isset at 0.14 [mm], and the lead thickness is set at 0.15 [mm].

By way of example, the lead frame LF is formed in such a way that a flatmaterial made of an alloy of iron (Fe)—nickel (Ni) system (whose Nicontent is, for example, 42 or 50 [%]) is subjected to an etchingprocess or a press work, thereby to form a predetermined lead pattern,whereupon the bending work for locating the die pad 3 below theconnection leads 5 is carried out for each of the four supporting leads4.

Next, the assembling process of the semiconductor device will bedescribed with reference to FIGS. 4, 6 and 7. FIGS. 6 and 7 areschematic sectional views for explaining a lead forming step.

First, the lead frame LF shown in FIG. 4 is prepared. Thereafter, asemiconductor chip 1 is mounted through an adhesive onto the chipmounting surface of the die pad 3 which is supported by the frame member8 of the lead frame LF through the supporting leads 4 as well as thelead supporting portions 7. Thereafter, electrodes 2 formed on thecircuit forming surface 1A of the semiconductor chip 1 and the innerlead portions 5A of the connection leads 5 supported by the frame member8 of the lead frame LF are electrically connected by pieces ofconductive wire 9. Thereafter, the semiconductor chip 1, the die pad 3,the supporting leads 4, the inner lead portions 5A of the connectionleads 5, and the wire pieces 9 are encapsulated with a sealing body 10on the basis of transfer molding technology. Thereafter, the tie bars 6tying the adjacent connection leads 5 are cut away. Thereafter, theouter lead portions 5B of the connection leads 5 are subjected to asolder plating treatment by electroplating.

Subsequently, the outer lead portions 5B of the connection leads 5 areformed into a gull-wing shape having root parts 5B1 each of whichprotrudes out of the sealing body 10, intermediate parts 5B2 each ofwhich bends downwards (onto the side of the rear surface of the frontand rear surfaces of the sealing body 10) from the root part 5B1, andmounting parts 5B3 each of which extends in the same direction as theextending direction of the root part 5B1 from the intermediate part 5B2.More specifically, the outer lead portions 5B of the connection leads 5are shaped into the gull-wing shape in such a way that, as illustratedin FIG. 6, the root part of each of the outer lead portions 5B isclamped by the protuberances of a lead keeper member 15A and a bendingbed 15B, while a bending punch 16 is brought into touch with the distalend part of the outer lead portion 5B, and that, as illustrated in FIG.7, the bending punch 16 is thereafter moved aslant toward theprotuberance of the bending bed 15B. Here at the lead forming step ofthe outer lead portion 5B, the defective lead forming of the outer leadportion 5B into the state in which it bends in the direction of arrayingthe connection leads 5 can be suppressed for the reason that, since theroot part 5B1 of the outer lead portion 5B is formed at the lead widthW1 equal to or greater than the lead thickness T, the mechanicalstrength of the root part 5B1 in the connection lead arraying directionbecomes higher than in case of forming the root part 5B1 of the outerlead portion 5B at a lead width less than the lead thickness T.

Subsequently, the distal end parts of the mounting parts 5B3 are cut offin order to properly locate the distal ends of the mounting parts 5B3 ofthe outer lead portions 5B. Thereafter, the supporting leads 4 are cutaway from the lead supporting portions 7 of the lead frame LF. In thisway, the semiconductor device 1 shown in FIGS. 1 through 3 issubstantially completed.

The semiconductor device thus constructed is mounted on a mountingsubstrate 20 as illustrated in FIG. 8 (a schematic perspective view ofthe essential portions of the semiconductor device in a state where thissemiconductor device has been mounted on the mounting substrate). Themounting of the semiconductor device is done in such a way that solderpaste layers are formed on the electrodes 20A of the mounting substrate20 by, for example, screen printing, that the semiconductor device isthereafter arranged on the mounting substrate 20 with the mounting parts5B3 of the respective outer lead portions 5B located on the electrodes20A through the corresponding solder paste layers, that the resultantmounting substrate 20 is thereafter conveyed into, for example, aninfrared reflow furnace, and that the solder paste layers are thereaftermolten, followed by hardening. Here at the mounting step of thesemiconductor device, solder bridges which appear across the mountingparts 5B3 of the outer lead portions 5B can be suppressed to suppressthe defective mounting of the short-circuit between the connection leads5 for the reason that, since the mounting part 5B3 of the outer leadportion 5B is formed at the lead width W3 less than the lead thicknessT, the interval between the respectively adjacent connection leads 5 atthe mounting parts 5B3 becomes broader than in case of forming themounting part of the outer lead portion 5B at a lead width equal to orgreater than the lead thickness T.

In this manner, the following effects are attained in accordance withthis embodiment:

Since the root parts 5B1 of outer lead portions 5B are formed at a leadwidth W1 being equal to or greater than a lead thickness T, themechanical strength of the root parts 5B1 in the direction of arrayingconnection leads 5 becomes higher than in case of forming the root parts5B1 of the outer lead portions 5B at a lead width less than the leadthickness T. It is therefore possible to suppress the defective leadforming that, in a lead forming operation for the outer lead portions5B, these outer lead portions 5B are formed into the state in which theybend in the connection lead arraying direction.

Besides, since the mounting parts 5B3 of the outer lead portions 5B areformed at a lead width W3 being less than the lead thickness T, theinterval between the respectively adjacent connection leads at themounting parts 5B3 becomes broader than in case of forming the mountingparts 5B3 of the outer lead portions 5B at a lead width equal to orgreater than the lead thickness T. It is therefore possible to suppresssolder bridges which appear across the mounting parts 5B3 of theadjacent leads 5 in soldering and mounting a semiconductor device onto amounting substrate 20, and to suppress the defective mounting that theadjacent connection leads 5 short-circuit.

By the way, this embodiment has been described concerning the examplewherein each of the outer lead portions 5B is molded into theconfiguration in which the tie bar separating part 5B4 is provided atthe intermediate part 5B2. However, each of the outer lead portions 5Bmay well be molded into a configuration in which a tie bar separatingpart 5B4 is provided at the root part 5B1.

Besides, although the example employing the lead frame made of the alloymaterial of Fe—Ni system has been described in this embodiment, it isalso allowed to employ a lead frame made of an alloy material of copper(Cu) system being superior in electric conductivity to the alloymaterial of Fe—Ni system. Since, in this case, the alloy material of Cusystem is softer than the alloy material of Fe—Ni system, the lead widthof the root parts 5B1 of the outer lead portions 5B should desirably beset somewhat broader than in the case of the embodiment describedbefore. Also, as illustrated in FIG. 9 (a schematic perspective view ofessential portions), the lead width of the entire intermediate part 5B2except the tie bar separating part 5B4 and a part on the side of themounting part 5B3 should desirably be set at the same lead width as thatof the root part 5B1.

While the invention made by the inventors has been concretely describedabove in conjunction with the embodiments, it is a matter of course thatthe present invention is not restricted to the foregoing embodiments,but that it is variously alterable within a scope not departing from thepurport thereof.

By way of example, the present invention is applicable to semiconductordevices of flat packaging type in which the outer lead portions ofconnection leads are set at a narrow pitch.

What is claimed is:
 1. A semiconductor device comprising: a sealingbody; a semiconductor chip which is formed with semiconductor elementsand a plurality of electrodes on its principal surface, and which isencapsulated with the sealing body; and a plurality of leads each ofwhich includes an inner portion that is electrically connected with thecorresponding electrode of the semiconductor chip and that lies withinthe sealing body, and an outer portion that extends from the innerportion continuously, that lies outside the sealing body and thatincludes a protruded part which extends in a direction away from asealing body, an intermediate part which bends downwards from theprotruded part, and a mounting part which extends from the intermediatepart in the same direction as the extending direction of the protrudedpart; wherein the protruded part has a width being equal to or greaterthan a thickness of the lead; and wherein the mounting part has a widthbeing less than a thickness of the lead.
 2. A semiconductor devicecomprising: a sealing body; a semiconductor chip which is formed withsemiconductor elements and a plurality of electrodes on its principalsurface, and which is encapsulated with the sealing body; and aplurality of leads each of which includes an inner portion that iselectrically connected with the corresponding electrode of thesemiconductor chip and that lies within the sealing body, and an outerportion that extends from the inner portion continuously, that liesoutside the sealing body; wherein each said outer portion includes afirst part which extends in a direction away from the sealing body, asecond part which bends downwards from the first part, a third partwhich extends from the intermediate part in a direction away from thesealing body, a first bent portion formed between the first part and thesecond part and a second bent portion formed between the second part andthe third part; wherein the first bent portion has a width equal to orgreater than a thickness of the lead; and wherein the third part has awidth less than a thickness of the lead.
 3. A semiconductor deviceaccording to claim 2, wherein the second bent portion has a width beingless than a thickness of the lead.
 4. A semiconductor device accordingto claim 3, wherein the second part has a tie bar separating part.
 5. Asemiconductor device according to claim 4, wherein the second part has anarrow part that has a width that is less than a thickness of the lead.6. A semiconductor device according to claim 5, wherein the second parthas a wide part which is wider than the narrow part between the narrowpart and the tie bar separating part.
 7. A semiconductor deviceaccording to claim 2, wherein the first bent portion is wider than thethird part.